Suture anchors have been developed for anchoring sutures during arthroscopic surgery with single side access. Such suture anchors are generally inserted with special tools for placement of the suture anchor and manipulation from one side of the body part after insertion.
One example of such a suture anchoring device is disclosed in U.S. Pat. No. 4,669,473 to Richards, et al. which is assigned to the assignee of the present invention. The Richards patent discloses a surgical fastener having a head portion and a filament portion normally arranged in a "T-shaped" configuration. The head portion has at least one pointed end so that when the head portion is implanted in body tissue, the head portion will attach itself securely to the body tissue. The surgical fastener is inserted by a tool including a hollow sheath through which the head of the T-shaped fastener is forced into position by a ram. The filament connected to the head is pulled with the head through a slot in the sheath. The resiliency of the fastener causes it to return to its normal T-shaped configuration with the head disposed generally transverse or at an acute angle to the filament. In this orientation, the pointed ends of the fastener head lodge themselves into the surrounding tissue. The tool is then removed leaving the free end of the filament extending from the tissue for subsequent use by the surgeon.
Another approach to providing a suture anchor intended to be anchored behind cartilage is disclosed in U.S. Pat. No. 4,741,330 to Hayhurst. The Hayhurst suture anchor also has a T-shaped configuration and is deployed for implantation with the ends of the head doubled over and pointing away from the filament. After insertion, the ends of the head due to their natural resiliency tend to return to their normal perpendicular orientation relative to the filament. Alternatively, the T-shaped anchor may be deployed with the filament folded over parallel to the head and forced into position through an elongated tubular insertion tool.
While the above surgical fasteners have proven to be dependable and effective, several disadvantages have been encountered which are addressed by the present invention. For example, the diameter of the opening in the body or tissue required for insertion in each of the above references must be greater than the combined diameter of the head of the T-shaped anchor and the filament. Also, the Richards' anchor is molded in one piece and includes a molded filament which may be more difficult to tie off than a conventional suture. With the Hayhurst anchor, joining the suture material to the plastic anchor sometimes involves intricate manufacturing and quality control procedures.
For arthroscopic procedures, the small space available to operate limits the size of instruments which can be used. Generally if such instruments are made smaller, they are more practical and can be used more efficiently and easily. Similarly, the smaller the hole required for insertion of the surgical instruments, the less trauma is caused to the patient by the operation and the less time it takes for the surgical site to heal.
The suture anchor and suture of the present invention, when installed according to the method of the present invention minimizes these and other problems.
Accordingly, it is a principal object of the present invention to provide an improved single-sided surgical suture fastener which minimizes the diameter of the insertion opening. Another object is to provide an improved surgical suture fastener which is simple and inexpensive to make.
A further object of the present invention is to provide an improved T-shaped suture anchor and a method of constructing it. Still another object is to provide an improved method for deploying a T-shaped surgical suture fastener.
Another object of the present invention is to provide an improved T-shaped suture anchor which has a stronger connection between the suture and the anchor and utilizes the full strength of the suture.
An additional object of the invention is to provide a T-shaped surgical suture fastener which has stop means on the suture for mating with a locking member and thereby being able to securely hold together pieces of tissue.